JP2017519141A - Vacuum pumping method and vacuum pump system - Google Patents

Abstract

The present invention includes a gas inlet orifice (2) connected to a vacuum chamber (1) and a gas outlet orifice (4) leading to a conduit (5) before coming out to a gas outlet (8) of a pumping system (SP). A primary dry screw type vacuum pump (3), a check valve (6) positioned in a conduit (5) between the gas outlet orifice (4) and the gas outlet (8), and a check valve ( The present invention relates to a pumping method in a vacuum pump system (SP) including an ejector (7) connected in parallel to 6). According to this method, a primary dry screw type vacuum pump (3) is put into operation and occurs simultaneously to pump the gas contained in the vacuum chamber (1) through the gas outlet orifice (4). In this manner, the working fluid is supplied to the ejector (7) and the primary dry screw type vacuum pump (3) pumps the gas contained in the vacuum chamber (1) and / or the primary dry screw type vacuum. The working fluid continues to be supplied to the ejector (7) as long as the pump (3) maintains a predetermined pressure in the vacuum chamber (1). The invention also relates to a pumping system (SP) that can be used to implement this method.

Description

  The present invention is that the main pump is a screw type dry vacuum pump, while the performance is improved in terms of flow rate and final vacuum in the vacuum pump system, which reduces the temperature of the outlet gas and the electrical energy consumption of the system. It relates to a pumping method that makes possible. The invention also relates to a vacuum pump system that can be used to implement the method according to the invention.

  In the industries such as chemical industry, pharmaceutical industry, vacuum deposition, semiconductor, etc., the overall trend to improve the performance of vacuum pumps to reduce the cost of installation and energy consumption, the performance in the drive, energy saving, bulk etc. In this respect, significant progress has been made.

  The state of the art proves that an auxiliary stage must be added to a multistage root type or multistage claw type vacuum pump in order to improve the final vacuum. For screw-type dry vacuum pumps, the screw must be given additional rotation and / or the internal compressibility must be increased.

  The rotational speed of the pump plays an extremely important role in defining the operation of the pump at different stages of chamber exhaust. Depending on the internal compression rate of commercial pumps (for example in the range 2-20), required for pumping stages at suction pressures between atmospheric pressure and about 100 mbar or called strong mass flow rate The power taken can be very high. The usual solution is to use a variable speed drive that allows the speed to decrease or increase and consequently capacity to decrease or increase depending on different criteria such as pressure type, maximum flow, limit torque, temperature, etc. That is. However, there is a decrease in flow rate at high pressure during operation at the reduced rotational speed, and the flow rate is proportional to the rotational speed. Variations in speed with the variable frequency drive provide additional cost and bulk. Another common solution is at a specific well-defined position in each of the specific stages in a multi-stage root-type or multi-stage claw-type vacuum pump, or along a screw in a screw-type dry vacuum pump. The use of a bypass type valve. This solution requires a large number of parts and raises reliability issues.

  The state of the art for vacuum pump systems aimed at improving the final vacuum and increasing the flow rate shows a root-type booster pump located upstream of the primary dry pump. This type of system works with bypass valves that are bulky and present reliability problems, or by employing means of measurement, checking, adjustment, or automatic control. However, these checks, adjustments, or automatic control means are piloted in an active manner that inevitably results in an increased number of system components, increased system complexity, and increased system cost. Must be operated.

  The invention has as its object the possibility of obtaining a better vacuum in a vacuum chamber than can be obtained with a single dry vacuum pump of the screw type (on the order of 0.0001 mbar). We must propose a method of pumping the vacuum pump system.

  The purpose of the present invention is to provide a pumping method for a vacuum pump system, which can increase the flow rate obtained at a pressure lower than the pressure that can be obtained by using a single screw type dry vacuum pump during pumping of the vacuum chamber. I have to suggest.

  The present invention likewise allows the purpose of placing the vacuum chamber under vacuum, reducing the electrical energy required to maintain the vacuum chamber, and reducing the temperature of the exit gas. The pumping method of the vacuum pump system must be proposed.

  These objects of the present invention are to provide a primary dry screw type vacuum with a gas inlet orifice connected to a vacuum chamber and a gas outlet orifice leading to a conduit with a check valve before exiting to the atmosphere or other device. It is obtained using a pumping method realized within the configuration of the pumping system, whose structure is essentially present in the pump. The ejector suction port is connected in parallel to the check valve, and the outlet of the ejector goes to the atmosphere or reconnects to the primary pump conduit after the check valve.

  Such a pumping method is in particular the subject of independent claim 1. Furthermore, different preferred embodiments of the invention are the subject matter of the dependent claims.

  Such a method is essentially the same as the primary dry screw type vacuum pump pumps the gas contained in the vacuum chamber through the gas inlet orifice, but also the primary dry screw type vacuum pump comes out. By discharging the gas through its outlet, it consists of continuously supplying the working fluid to the ejector and operating the ejector while maintaining a predetermined pressure (eg, final vacuum) in the chamber.

  According to a first aspect, the present invention provides a primary dry screw type vacuum pump and ejector connection with separate measurement results and devices (eg, sensors for pressure, temperature, current, etc.), automatic control or data management and The fact is that no operation is required. As a result, a vacuum pump system suitable for implementing the pumping method of the present invention has a minimal number of components, has excellent simplicity, and is much cheaper than existing systems.

  According to the second aspect, the present invention allows the novel dry pumping method to allow the primary dry screw type vacuum pump to operate the one of the distribution network at a single constant speed according to its own mode of operation. Or in the fact that it can be rotated at a variable speed. As a result, the complexity and cost of a vacuum pump system suitable for implementing the pumping method of the present invention can be further reduced.

  Due to its nature, the ejector integrated in the vacuum pump system can always function without damage according to this pumping method. Ejector sizing depends on the minimum consumption of working fluid to operate the device. The ejector is usually a single stage. The nominal flow rate of the ejector is selected according to the enclosed space of the outlet conduit of the primary dry screw type vacuum pump that is limited by the check valve. The flow of the ejector can be 1/500 to 1/20 of the nominal flow rate of the primary dry screw type vacuum pump, but it can be less than these values or more than these values. it can. The ejector working fluid can be compressed air, but can also be other compressed gases (eg, compressed nitrogen). The check valve placed in the outlet conduit of the primary dry screw type vacuum pump can be a standard component that is commercially available. The check valve is dimensioned according to the nominal flow rate of the primary dry screw type vacuum pump. Specifically, the check valve is expected to close when the pressure at the suction end of the primary dry screw type vacuum pump is between 500 millibar absolute pressure and the final vacuum (eg, 100 millibar).

According to another variant, the ejector is multi-stage.
According to yet another variant, the ejectors may be made of materials with increased chemical resistance to substances and gases normally used in the semiconductor industry, single-stage ejector variants and those in multi-stage ejectors.
The ejector is desirably small in size.

According to another variant, the ejector is integrated in a cartridge incorporating a check valve.
According to yet another variant, the ejector is integrated into a cartridge incorporating a check valve, which is itself housed in an exhaust muffler secured to the gas outlet orifice of the primary dry screw type vacuum pump. ing.
In accordance with the operation of the vacuum pump system according to the present invention, the ejector always pumps in the sealed space between the gas outlet orifice of the primary dry screw type vacuum pump and the check valve.

  According to yet another variant of the invention, the flow rate of gas at the pressure required for the operation of the ejector is supplied by a compressor. In a noteworthy manner, this compressor can be driven by at least one of the shafts of a primary dry screw type vacuum pump, or alternatively or additionally, in an autonomous manner, a primary dry screw type vacuum. It can be driven independently from the pump. The compressor can exhaust the atmosphere or gas in the gas outlet conduit after the check valve. The presence of such a compressor makes the screw-type vacuum pump system independent of the compressed gas source, which can be suitable for a particular industrial environment.

  Beginning with the chamber evacuation cycle, the chamber pressure increases, for example, to equal atmospheric pressure. Considering the compression with the primary dry screw type vacuum pump, the pressure of the gas released at the outlet of the primary dry screw type vacuum pump is higher than the atmospheric pressure (when the gas at the outlet of the primary pump is released directly into the atmosphere) Or higher than the pressure at the inlet of another device connected downstream. This causes the check valve to open.

  When the check valve is opened, the ejector movement is felt very slightly because the pressure at the ejector inlet is approximately equal to the pressure at the ejector outlet. In contrast, when the check valve closes at a certain pressure (because the pressure in the chamber has dropped in the meantime), the movement of the ejector causes the pressure difference between the chamber and the conduit behind the valve to gradually increase. Cause a decline. The pressure at the outlet of the primary dry screw type vacuum pump is the pressure at the inlet of the ejector, and the pressure at the outlet of the ejector is always the pressure in the conduit after the check valve. The more the ejector pumps, the lower the pressure at the outlet of the primary dry screw type vacuum pump in the closed space limited by the closed check valve, and consequently the primary dry screw type vacuum pump. The pressure difference between the chamber and the outlet is reduced. This slight difference reduces the internal leakage in the primary dry screw type vacuum pump, resulting in a reduction in chamber pressure that improves the final vacuum. Further, the primary dry screw type vacuum pump consumes energy for compression so as to gradually decrease, and generates heat for gradually decreasing compression heat.

  On the other hand, the study of the mechanical concept intends to reduce the sealed space between the gas outlet orifice of the primary dry screw type vacuum pump and the check valve in order to reduce the pressure in the sealed space more quickly. It is also clear.

  The singularities and advantages of the present invention will be more fully understood in the context of the description, which can be understood by way of example given in an illustrative manner, in a non-limiting manner with reference to the accompanying drawings shown. It should be clear.

It is the figure which showed typically the vacuum pump system suitable for implement | achieving the pumping method according to the 1st Embodiment of this invention. It is the figure which showed typically the vacuum pump system suitable for implement | achieving the pumping method according to the 2nd Embodiment of this invention.

FIG. 1 shows a vacuum pump system (SP) suitable for realizing the pumping method according to the first embodiment of the present invention.
The vacuum pump system (SP) includes a chamber 1 connected to a suction orifice or intake port 2 of a primary dry screw type vacuum pump 3. The gas outlet orifice of the primary dry screw type vacuum pump 3 is connected to a conduit 5. A check valve 6 is placed in the conduit 5 and the conduit 5 follows this check valve to the gas outlet conduit 8. When closed, the check valve 6 enables the formation of a sealed space 4 that is accommodated between the gas outlet orifice of the primary dry screw type vacuum pump 3 and the valve itself. The vacuum pump system (SP) also includes an ejector 7 connected in parallel to the check valve 6. The intake port of the ejector is connected to the sealed space 4 of the conduit 5, and the release orifice of the ejector is connected to the conduit 8. The supply pipe 9 supplies the working fluid of the ejector 7.

  By setting the primary dry screw type vacuum pump 3 to the operating state, the working fluid of the ejector 7 is injected by the supply pipe 9. The primary dry screw type vacuum pump 3 sucks the gas in the chamber 1 through the connected conduit 2 at the inlet of the primary dry screw type vacuum pump 3 and then at the outlet of the primary dry screw type vacuum pump 3. The gas is compressed to release the gas into the conduit 5 passing through When the pressure for closing the check valve 6 is reached, the valve closes. Starting from this moment, the pressure in the sealed space 4 gradually decreases to the pressure limit value by the pumping of the ejector 7. In parallel, the power consumed by the primary dry screw type vacuum pump 3 gradually decreases. This occurs for a short period of time (eg during a cycle that occurs every 5-10 seconds).

  By appropriately adjusting the flow rate of the ejector 7 and the pressure of closing the check valve 6 according to the flow rate of the primary dry screw type vacuum pump 3 and the sealed space of the chamber 1, the check valve 6 is closed with respect to the duration of the exhaust cycle. It is further envisaged to reduce the previous time and thus reduce the loss of working fluid during this operating time of the ejector 7 without affecting the pumping. In addition, these very small “losses” allow for an assessment of the overall amount of energy consumption. In contrast, the advantage of ease provides superior system reliability and 10% to 20% compared to similar automated pumps with programmable automatic devices and / or variable speed drive units, control valves, sensors, etc. % Cheap price.

FIG. 2 shows a vacuum pump system (SP) suitable for carrying out the pumping method according to the second embodiment of the present invention.
In contrast to the system shown in FIG. 1, the system shown in FIG. 2 further comprises a compressor 10 that supplies a gas flow rate at the pressure required for the function of the ejector 7. In practice, the compressor 10 can suck the atmosphere or gas in the gas outlet conduit 8 after the check valve 6. The presence of the compressor 10 makes a vacuum pump system independent of the compressed gas source that can be suitable for a particular industrial environment. The compressor 10 can be driven by at least one shaft of the primary dry screw type vacuum pump 3 or by an electric motor of the compressor 10 itself, and thus in a completely independent manner from the primary dry screw type vacuum pump 3. In all cases, the energy consumption to be able to supply the gas flow rate at the pressure required to operate the ejector 7 is far greater than the savings realized with the energy consumption of the primary dry screw type vacuum pump 3. (For example, on the order of 3% to 5%).

  Indeed, the present invention is subject to numerous variations with respect to its implementation. Although various embodiments have been described, it is well understood that it is not possible to identify all possible embodiments in a comprehensive manner. Of course, it is envisaged that one means described will be replaced by an equivalent means without departing from the scope of the invention. All these modifications form part of the general knowledge of those skilled in the art of vacuum technology.

Claims (30)

A gas inlet orifice (2) connected to the vacuum chamber (1) and a gas outlet orifice (4) leading to a conduit (5) before coming out to the gas outlet (8) of the vacuum pump system (SP) A primary dry screw type vacuum pump (3);
A check valve (6) positioned in the conduit (5) between the gas outlet orifice (4) and the gas outlet (8);
An ejector (7) connected in parallel to the check valve (6), and a vacuum pumping method in a vacuum pump system (SP),
The primary dry screw type vacuum pump (3) is placed in operation to pump gas contained in the vacuum chamber (1) through the gas outlet orifice (4);
Working fluid is supplied to the ejector (7) in a simultaneous manner,
While the primary dry screw type vacuum pump (3) pumps the gas contained in the vacuum chamber (1) and / or the primary dry screw type vacuum pump (3) is in the vacuum chamber (1). A pumping method for a vacuum pump system (SP), characterized in that a working fluid is continuously supplied to the ejector (7) while maintaining a predetermined pressure in the vacuum pump system (SP). In the pumping method of Claim 1,
The pumping method according to claim 1, wherein the outlet of the ejector (7) is reconnected to the conduit (5) after the check valve (6). In the pumping method according to claim 1 or 2,
Pumping method, characterized in that the ejector (7) is dimensioned to have a minimum consumption of working fluid. In the pumping method in any one of Claims 1-3,
The nominal flow rate of the ejector (7) is selected according to the sealed space of the conduit (5) of the primary dry screw type vacuum pump (3) limited by the check valve (6). Pumping method. In the pumping method of Claim 4,
The pumping method according to claim 1, wherein a flow rate of the ejector is 1/500 to 1/20 of a nominal flow rate of the primary dry screw type vacuum pump (3). In the pumping method in any one of Claims 1-5,
The pressure feeding method, wherein the working fluid of the ejector (7) is compressed air and / or nitrogen. In the pumping method in any one of Claims 1-6,
The pumping method according to claim 1, wherein the ejector (7) is single-stage or multi-stage. In the pumping method in any one of Claims 1-7,
The pumping method according to claim 1, wherein the check valve (6) is closed when the pressure at the suction end of the primary dry screw type vacuum pump (3) is between 500 millibar absolute pressure and the final vacuum. In the pumping method in any one of Claims 1-8,
The said ejector (7) is made from the material which raised the chemical resistance with respect to the substance and gas normally used in the semiconductor industry, The pumping method characterized by the above-mentioned. In the pumping method in any one of Claims 1-9,
The pressure feeding method, wherein the ejector (7) is integrated with a cartridge incorporating the check valve (6). In the pumping method of Claim 10,
The pressure feeding method, wherein the cartridge is accommodated in an exhaust muffler fixed to a gas outlet orifice (4) of the primary dry screw type vacuum pump (3). In the pumping method in any one of Claims 1-11,
A gas feed method characterized in that the flow rate of gas at a pressure required for the function of the ejector (7) is supplied by a compressor (10). The pumping method according to claim 12,
The compressor (10) is driven by at least one of the shafts of the primary dry screw type vacuum pump (3). The pumping method according to claim 12,
The compressor (10) is driven by an autonomous method independently from the primary dry screw type vacuum pump (3). In the pumping method in any one of Claims 12-14,
The compressor (10) exhausts the gas in the gas outlet (8) after the atmosphere or the check valve (6). A gas inlet orifice (2) connected to the vacuum chamber (1) and a gas outlet orifice (4) leading to a conduit (5) before coming out to the gas outlet (8) of the vacuum pump system (SP) A primary dry screw type vacuum pump (3);
A check valve (6) positioned in the conduit (5) between the gas outlet orifice (4) and the gas outlet (8);
A vacuum pump system (SP) comprising an ejector (7) connected in parallel to the check valve (6),
While the primary dry screw type vacuum pump (3) pumps the gas contained in the vacuum chamber (1) and / or the primary dry screw type vacuum pump (3) is in the vacuum chamber (1). A vacuum pump system (SP) characterized in that the ejector (7) is designed such that a working fluid can be supplied to the ejector (7) while maintaining a predetermined pressure therein. The vacuum pump system according to claim 16, wherein
Vacuum pump system, characterized in that the outlet of the ejector (7) reconnects to the conduit (5) after the check valve (6). The vacuum pump system according to claim 16 or 17,
Vacuum pump system characterized in that the ejector (7) is dimensioned to have a minimum consumption of working fluid. The vacuum pump system according to any one of claims 16 to 18,
The nominal flow rate of the ejector (7) is selected according to the sealed space of the conduit (5) of the primary dry screw type vacuum pump (3) limited by the check valve (6). Vacuum pump system. The vacuum pump system according to claim 19,
The vacuum pump system according to claim 1, wherein a flow rate of the ejector is 1/500 to 1/20 of a nominal flow rate of the primary dry screw type vacuum pump (3). The vacuum pump system according to any one of claims 16 to 20,
The vacuum pump system according to claim 1, wherein the working fluid of the ejector (7) is compressed air and / or nitrogen. The vacuum pump system according to any one of claims 16 to 21,
The said ejector (7) is a single stage or multistage, The vacuum pump system characterized by the above-mentioned. The vacuum pump system according to any one of claims 16 to 22,
The check valve (6) closes when the pressure at the suction end of the primary dry screw type vacuum pump (3) is between 500 millibar absolute pressure and the final vacuum. The vacuum pump system according to any one of claims 16 to 23,
The said ejector (7) is made from the material which raised the chemical resistance with respect to the substance and gas normally used in the semiconductor industry, The vacuum pump system characterized by the above-mentioned. The vacuum pump system according to any one of claims 16 to 24,
The vacuum pump system, wherein the ejector (7) is integrated with a cartridge incorporating the check valve (6). The vacuum pump system according to claim 25,
The vacuum pump system, wherein the cartridge is housed in an exhaust muffler fixed to a gas outlet orifice (4) of the primary dry screw type vacuum pump (3). The vacuum pump system according to any one of claims 16 to 26,
The vacuum pump system further comprising a compressor (10) for supplying a gas flow rate at a pressure required for the function of the ejector (7). The vacuum pump system of claim 27,
The vacuum pump system, wherein the compressor (10) is driven by at least one of shafts of the primary dry screw type vacuum pump (3). The vacuum pump system of claim 27,
The vacuum pump system, wherein the compressor (10) is driven independently of the primary dry screw type pump (3) in an autonomous manner. The vacuum pump system according to any one of claims 27 to 29,
The vacuum pump system characterized in that the compressor (10) exhausts the gas in the gas outlet (8) after the atmosphere or the check valve (6).

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